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Solve for x: 4(3x+7)=7
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- you want to get rid of the brackets, to do this multiply the numbers in brackets by 4
- rewrite the question, it should now be 12x + 28 =7
- now you want to isolate x, to do this subtract 28 from both sides of the equation
- rewrite the equation once again, it should now be 12x = -21
- now divide both sides of the equation by 12
- rewrite the equation one more time and you have your answer. x= -1.75
- dont forget to check your answer! :)
im not sure how your teacher asked you to solve the equations, but theres simple steps to follow to figure out for x;
Posted by buffy-the-vampire-slayer on June 6, 2009 at 8:48 AM (Answer #1)
(3x+7)=7/4 divide both sides by 4
3x = 7/4 - 7 subtract 7 from both sides
x = (7/4 - 7)/3 divide both sides by 3
x = 7/12 -7/3 expand the parenthesis
x = 7/12 - 28/12 find common denominator (* by 4/4)
x = -21/12 subtract
x = -7/4 simplify
Posted by kjcdb8er on June 6, 2009 at 8:48 AM (Answer #2)
High School Teacher
To solve for x, multiply by 4 to each of the terms inside the bracket in the left side:4*3x=12x. 4*-7=-28. The right side is retained as it is:
Subtract 28 from both sides to retain the unknown term 12x on the left and the known term or the numbers on the right:
Now 28-28 on the left cancel out.On the right 7-28= -21:
Divide both sides by 12. On the left 12x/12 becomes x.On the right -21/12, which is reduced to -7/4 in the lowest equivalent fraction form.
Therefore, x=-7/4 .
Convert 7/4 in decimal form and attach the minus line at last.
Therefore,x=-1.75 is our solution.
Put the solution, x=-1.75 in the original equation and see whether the equation is satisfied, in the sense the value on the left becomes equal to the right.
Left side :4*[3(-1.75)+7]=4*3(-1.75)+4*7=4*-5.25+28=-21+28=7.
Both sides are equal in value after putting x=-1.75. So the solution is verified.
Posted by neela on June 6, 2009 at 11:26 AM (Answer #3)
4(3x+7)=7 ======>multiply 4 by 3x , 7
12x + 28 = 7 ========> add -28 both side
12x + 28 -28 = 7-28
12x = -21 =======> divid both side by 12
x = -21/12 = 1.75
Posted by fahad-alfahad on June 6, 2009 at 1:01 PM (Answer #4)
Middle School Teacher
4(3x + 7) = 7
1) You can't do anything until you get rid of the parentheses. Use distributive property to get rid of those.
12x + 28 = 7
2) Now do the order of operations backwards. The first thing (going backwards) is addition/subtraction. What do you have in your problem? You have addition. The opposite of addition is subtraction.
12x + 28 = 7
12x = -21
3. Now you have 12x = -21. What operation is being used in the equation? Multiplication is. The opposite of multiplication is division. Now divide both sides by 12.
12x = -21
x = -1.75
Posted by sbinkowski on June 14, 2009 at 6:01 AM (Answer #5)
Posted by fcooper15 on February 18, 2010 at 11:49 AM (Answer #6)
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